Bob Sang, who has died of acute pancreatitis aged 61, pioneered the idea of involving patients and the public in the design and improvement of health and social care services. At a time when such thinking met indifference, derision or outright hostility, he succeeded in getting the argument heard through a combination of dogged but good-natured persistence and an inexhaustible capacity to create networks of people with a common interest. He lived to see his vision become mainstream policy, indeed in part a statutory requirement, and his own contribution recognised by professorial status.

Terms such as "user involvement", "patient voice" and "co-production of services" now roll off the tongue of every health or social care manager. But this is a relatively recent trend. For at least half a century after the founding of the modern welfare state, the unquestioned arrangement was that the professional decided what was right for the citizen, and the citizen showed due gratitude.

Only two years ago, Sang wrote: "A deep, taken-for-granted assumption in our culture is that if you have a 'problem' or 'need', you get a label: 'patient', 'user', 'client', 'sick', 'disabled', 'handicapped'. One consequence of such labelling is the separation of citizens into categories and groups defined by the service models that have been constructed to 'meet this need/problem'. Very powerfully, at the point of diagnosis and analysis, individuals are defined only by their 'special needs' and/or their dysfunctioning, thus excluding their many purposes, roles, capabilities and aspirations as parents, partners, entrepreneurs, citizens."

He made it his mission to realise those purposes, roles, capabilities and aspirations and to get rigid health and social care systems to open up to them. The systems are now, to varying degrees, duty-bound to listen to the views of those they serve, and to reflect what they hear in the way services are crafted. But more, the vogue for "personalisation" of services involves their users in shaping them to their individual needs and wishes, up to and including giving them the cash to shop around for what they think suits them best. This "personal budget" approach has been developed in social care and is now being extended into the NHS for people with long-term conditions.

Sang came to his mission via a circuitous route. Born in London but raised in Edinburgh - he considered himself an honorary Scot - he at first sought to follow the path of his scientist parents, but failed his chemistry degree at the University of East Anglia. A succession of jobs followed around the Brighton area, where his family had relocated and which he was to make his base. These jobs included hospital porter, care assistant for people with learning disabilities, and what would now be called outreach worker for the employment service. On more than one occasion, he faced disciplinary measures or left a post because of his tendency to see things from the perspective of the recipient of the service he was providing, which brought him into conflict with management.

Another factor was that he had himself become an episodic user of mental-health services following his failed degree course, and observed at first hand the raw deal that users got and the power imbalance between them and their care providers.

Sang returned to studying and completed a public administration degree at Sussex University. He went on to work at Sussex and Brighton universities and at the King's Fund health thinktank, and was appointed by South Bank University as the UK's first professor of patient and public involvement. Recently, he served as special adviser to the Commons health select committee's inquiry into patient and public involvement in health.

He co-founded a consultancy, Sang Jacobsson, through which he did much of his most important paid work. This was largely in the public services, but he did undertake IT-related organisational development projects in industry, notably a long-term project for the telecoms company Ericsson.

Just as important to him, though, was his tireless and often unpaid work for citizens' advocacy groups for people with learning disabilities - he helped set up the first such programme in 1982 - and for organisations such as the Patients Association and the Employers' Forum on Disability. He was a compulsive networker. Any chance meeting would invariably lead to a phone call or email with "some thoughts", an article or two to read and reflect upon and an introduction to a third party "you might find interesting". His was a well-known face among Brighton-to-London commuters. On one occasion, a friend recalls, he had fully half a train carriage engaged in a discussion about stress at work.

There were signs of the feverish pace of work slowing just a little. In recent years, he had begun to work with a group of colleagues from the worlds of PR and digital media on a vision of a social network and mentoring programme for "health entrepreneurs" who might take forward some of his ideas. After his sudden death, such heirs of his intellectual legacy will have a huge void to fill.

Sang is survived by his wife, Lisa, children Katherine, Marion and James, and grandchildren Johnathon and Jack.

• Robert Sang, health and social care reformer, born 27 March 1948; died 5 June 2009